A liquid or gel bipropellant rocket propulsion system consists of gas generators, oxidizer and fuel propellant tanks, plumbing, oxidizer and fuel valves, and an engine. This propulsion unit begins operation when the gas generators have been initiated and the gases from the gas generator pressurize oxidizer and fuel propellant tanks. When the oxidizer and fuel valves open, the pressurized oxidizer and fuel tanks then force the propellants through the plumbing into the engine where the propellants are mixed and ignited. The propellants can be ignited by either ignition aids or by hypergolic chemical reaction. Ignition aids can take up valuable space in the propulsion system so a hypergolic chemical reaction is the preferred ignition method. Inhibited Red Fuming Nitric Acid (IRFNA) type IIIB and monomethyl hydrazine (MMH) ignite when contacted with each other because of a hypergolic chemical reaction and are the preferred oxidizer and fuel for bipropellant rocket propulsion systems. These propellants can deliver a specific impulse of 284 lbf sec/Ibm and density impulse of 13.36 lbf sec/cubic inch when the engine operating pressure is 2000 psi. Special precautions must be used when handling because of its toxic properties.
If a liquid gas generator is used excess pressurizing gases do not have to be dumped overboard to prevent overpressurization that can result from a solid gas generator formulation. A solid gas generator formulation once ignited cannot be stopped; however, a liquid gas generator system supplies gas pressure only when it is needed. Hydrazine and hydrazine blends have considered for liquid gas generators because of their ability to decompose at ambient conditions on an iridium catalyst to form warm (100.degree. F. to 1500.degree. F.) gases. Hydrazine is undesirable because of its toxicity and high melting point (34.degree. F.).
An object of this invention is to provide a less toxic hypergolic fuel gel propellant that is a suitable replacement for MMH.
Another object of this invention is to provide a less toxic hypergolic fuel gel propellant that is a suitable replacement for MMH which has a competitive density impulse for the same engine operating conditions.
A further object of this invention is to provide alternative fuels selected from tertiary amine azides that can function as hypergolic fuels in a bipropellant propulsion system that meet the above conditions as further defined hereinbelow.